if you can grab and crate her and microchip her at the vets? she can have a catflap into her home there. that only opens for her.
You can also add outdoor dens (wooden and waterproofed) if you buy online. (and catflap/microship those to only open for her).
with time and trust have you got her to stay indoors ? .. in a room for a while? (how long now?)
Have you made this 1st ''safe room'' (the entrance room?) welcomeing with a tree and toys , bed in a corner den maybe? ... does she freak if you close the door?
You may be able to get this girl to be indoor/outdoor pet with you, in time and have her vet registered ect (insured too if you wish).
more pics pls